Electro-Magnetic Acoustic Imaging (EMAI) technologies have developed significantly over the last several decades; in a large part to the Applicants' own seminal works. For example, EMAI technologies are described in great detail in co-owned U.S. Pat. No. 6,535,625 to Chang et al. titled “Magneto-Acoustic Imagining” filed on Sep. 24, 1999 and co-owned U.S. Pat. No. 6,974,415 to Cerwin et al. titled “Electromagnetic-Acoustic Imagining” filed on May 22, 2003.
It was appreciated early on that one could use Time-Reversed Mirroring (TRM) of ultrasonic signals to treat target tissues. For example, the papers titled “Time Reversal of Ultrasonic Fields—Part I: Basic Principles” and “Time Reversal of Ultrasonic Fields—Part II: Experimental Results” by Fink et al., published in September 1992, describe in great detail time reversing ultrasonic acoustic signals. Further effort toward developing TRM ultrasound technologies is described in U.S. Pat. No. 5,428,999 to Fink titled “Method and Apparatus for Acoustic Examination Using Time Reversal” filed on Sep. 24, 1993, and U.S. Pat. No. 6,755,083 to Berryman titled “Method for Distinguishing Multiple Targets Using Time-Reversal Acoustics” filed Apr. 22, 2002.
The Applicants also provided pioneering insight into combining the two technologies where electro-magnetically induced acoustic ultrasounds could be time-reversed and mirrored back toward an originating internal target tissue as described in U.S. patent application publication U.S. 2007/0038060 to Cerwin et al. titled “Identifying and Treating Bodily Tissues Using Electromagnetically Induced, Time-Reversed, Acoustic Signals” filed on Jun. 9, 2006. At the time, the Applicants focused on applying an amplified TRM ultrasound signal back toward a detected conductivity gradient, possibly to ablate a target tissue.
These and all other extrinsic materials discussed herein are incorporated by reference in their entirety. Where a definition or use of a term in an incorporated reference is inconsistent or contrary to the definition of that term provided herein, the definition of that term provided herein applies and the definition of that term in the reference does not apply.
The Applicants have come to further appreciate that a wealth of information is available regarding a subject area of interest that can be brought to bear when constructing a TRM ultrasound signal to target a specific tissue. Previously, induced ultrasound signals were filtered to enhance reception of only signals having a frequency twice the frequency of an input RF signal. Additionally, the received ultrasound signals were only mirrored back toward a conductivity gradient. Applicants have now appreciated received acoustic data of an induced acoustic signal represents a measurement of a conductive topology, as opposed to just an indicator that a conductivity gradient is present. The acoustic data reflects properties of a full conductivity topology and by extension properties of the tissues within the subject area under consideration. One can collect and use the acoustic data to derive parameters associated with the conductivity topology to deduce or derive various properties of the subject tissue area. The measured parameters can then be used to tailor a TRM acoustic treatment signal to apply therapy to a target tissue within the subject area. One should appreciate that conductivity topologies can be combined with other topologies (e.g., mechanical, acoustic, density, etc.) to create a hybrid topology that can be brought to bear for clinically useful results (e.g., diagnosis, treatment, etc.)
Unless the context dictates the contrary, all ranges set forth herein should be interpreted as being inclusive of their endpoints, and open-ended ranges should be interpreted to include commercially practical values. Similarly, all lists of values should be considered as inclusive of intermediate values unless the context indicates the contrary.
Thus, there is still a need for time-reversed mirroring of electro-magnetically induced acoustic signals.